Telephone system



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Filed March l0, 1936 10 Sheets-Sheet 8 Aug- 10, 1937. F. J. scUDDER IELEPHONE SYSTEM Filed March l0, 1956 l0 Sheets-Sheet 9 EJ. SCUDDER A TTORNEV F. J. SCUDDER TELEPHONE SYSTEM Filed Maron 1o, 193e 1o sheets-sheet 1o 4 COQ FJSCUDDER ATTORNEY Patented Aug. 10, 1937 ATENT FFLCE TELEPHONE SYSTEM York Application March 10, 1936, Serial No. 68,044

9 Claims.

This invention relates to telephone systems and particularly to those in which message-registers are used for assessing charges for the service rendered.

The object of the invention is to simplify and improve the equipment for obtaining and recording information concerning the destination of a call and for utilizing this information to assess charges on the basis of the sone called and also on the basis of the duration of the call;

It has been proposed heretofore to provide a group of trunk circuits with a common messageregister operating device which is connected to a calling one of said trunks and receives information as to the called zone to determine the rate of charge of the call. Such a system is shoWn in the patent to Johnson et al. 1,859,924 of May24,

1932. In the arrangement of this patent a single message-register control device is provided 2O for a plurality of trunks and is connected periodically to each trunk on which it is necessary to assess a charge. Also the zone information, from which the value of the charge for any particular call is determined, is received by the com- 25 mon register operating device from the trunk circuit to which it has connected, this information having first been set up in the trunk in accordance with the number dialed and recorded in the register-sender. It has also been propose-d to employ in systems of the step-by-step type, where central o-iiice register-senders are not utilized, a plurality of message-register operating devices in common to a group of conversational trunks. The iirst idle one of the com- 35 moa operating devices is taken in use when a call appears and is connected to the calling trunk preparatory to receiving the zone information after the designation digits are dialed by the calling subscriber.

According to the present invention, improvements are secured over the prior art arrangements by means of a system in which a plurality of zone and time-controlled message-register operating devices are provided in common to a group of conversational trunks, and in which the conversational. connections are established under the control of a digit recording mechanism at the central office. Whenever a call is made involving one of said trunks, an idle one of the message-register operating devices is chosen and is connected by means of selective switches to the calling trunk. The idle operating device thus selectively connected to the calling trunk is also connected, independently of the trunk, to the f -55 common digit recording mechanism in which the dialed number has been recorded. In this way the information as to the zone is received by the message-register operating device directly from the digital recording device, and this information need not be established in the trunk circuit.

Another feature is a testing and operating mechanism comprising a series of relays common to all of the meter operating devices and to all of the switches that'serve to connect these devices to the trunk circuits, together with means, depending on which trunk is calling, for associating said mechanism with said devices to test them for an idle one, to cause the connection of the chosen idle operating device with the digitV recording register which has received the dialed number, and to operate the proper connecting switch to connect said idle device to the calling trunk. i

A further feature of the invention is an arrangement by which said register operating devices are divided into a plurality of groups, certain groups serving respectively diiferent groups of trunks and at least one of said groups of devices serving a plurality of said groups of trunks.

These and other features of the invention will be more clearly understood from the following etailed description, which should be taken in conjunction with the accompanying drawings, and also from the appended claims.

Referring to the drawings, Figs. 1 to 5 inclusive, when taken in the order shown in Fig. 11, illustrate schematically the relationship between the various circuit elements involved in the application of the present invention to a telephone system of the cross-bar type and also show, in a o general way, the manner in which connections are established between one of a common group of Zone and time-controlled message-register operating devices and a conversational trunk over which a call is being made.

Fig. 1 shows a calling subscribers station and a portion of the primary and secondary line switches and line links over which the callingA line is extended to the district trunks and the district frame.

Fig. 2 shows a district trunk circuit and a portion of the district frame primary and secondary switches by means of which the calling line is further extended toward the called station.

Fig. 3 shows a portion of the primary and secondary sender selector switches by means of which connections are established between the calling line and an idle subscribers registersender, a decoder marker circuit, a connector circuit for establishing connections between the sender and the decoder marker, and a district frame connector circuit by means of which' connections are established between the decoder marker and the district frame.

5 Fig. 4 shows two of the ve zone and timing device connecting switches which serve to connect idle zone and timing devicesto any of the one hundred district trunks appearing on the district frame with which these five connecting switches are associated. Fig. 4 also shows certain group and test relays associated with the connecting switches.

Fig. 5 shows schematically a portion of the zone and timing devices which, by means of the connecting switches shown in Fig. 4, are accessible to the district trunks appearing on the district frame shownin Fig. 2. Fig. 5 also shows certain relays, one for each zone and timing device, which serve to establish control connections between the zone and timing device and the decoder marker, through the district frame connector circuit shown in Fig. 3.

Figs. 6 to 10 inclusive, when taken in the order shown in Fig. 12, illustrate the system more in detail.

Fig. 6 shows a calling subscribers station, a portion of a primary and a secondary line switch over which lines are extended to the district frame, certain relays of the district trunk circuit, and 30 the meter operating device, individual to the district trunk, which provides for the operation of the subscribers message register on local calls.

Fig. '7 shows a portion of a primary and a secondary switch of the district frame, certain district frame relays, and a called subscribers station.

Fig. 8 shows portions of a primary and a secondary sender selector switch, a subscribers register-sender, such portions of a decoder marker cir- 40 cuit as are involved in the control of the zone and timing devices, and portions of a decoder marker connector and a district frame connector circuit.

Fig. 9 shows portions of two of the ten zone 45 and timing device connecting switches which serve the one hundred district trunks of a district frame, together with certain associated group and test relays.

Fig. 10` shows portions of one zone and tim- 50 ing device, certain relays for associating any one of a plurality of these devices with a decoder marker circuit for control purposes, and also certain checking and alarm equipment associated with the zone and timing devices.

55 Fig. 11 shows the manner in which Figs. 1 to 5 inclusive are arranged.

Fig. 12 shows the manner in which Figs. 6 to 10 inclusive are arranged.

Switches |03, iM, |05, 200, 20|, 202, 203, 350, 60 39|, 400, sill, 603, 604, '|00 102, 000, 80|, 909, and @EN of Figs. l, 2, 3, 4, 6, 7, 8, and 9 are of the cross-bar type and consist briefly of a plurality of sets of contacts arranged in horizontal and vertical rows or units. Associated with each hori- 65 zontal row of contact sets is a horizontal operating magnet known as a select magnet, under control of which the said horizontal contact sets are prepared for operation. Associated with each vertical row of contact sets is a vertical magnet known 70 as a hold magnet under control of which any set of contacts in that vertical row, after being prepared by the operation of its respective horizontal select magnet, is operated and held in the operated position until the release of the vertical 75 magnet takes place. For a more detailed explanation of the construction and operation of these cross-bar switches reference may be had to the patent to J. N. Reynolds, No. 2,021,329, granted November 19, 1935.

Only such portions of the line switch, district trunk, district frame, sender selector, sender, decoder marker, decoder marker connector and district frame connector circuits are shown as are required for a clear understanding of the invention, For a more detailed explanation and description of the operation of a systemof the type to which the present invention is applicable reference may be had to the copending application of W. W. Carpenter, Serial No. 27,305, led June 19, .1.935.

Referring to Figs. 1 to 5 inclusive, a general description will now be given to illustrate the application of this invention to a telephone system of the cross-bar type. Line |0| of subscribers station l0@ is shown connected to the left vertical row of contacts oi primary line switch |03, the vertical rows of contacts lof this primary switch having access, over ten line links such as links M6 and lll', to one of the ten vertical rows of contacts of each of ten secondary line switches. Each of the ten horizontal rows of contacts of each secondary line switch extends to a district trunk circuit and thence to one of ten horizontal rows of contacts of a district frame primary switch. For example, the upper horizontal row of contacts of secondary line switch |04 extends over conductors ||0 to district trunk 2|5 and to the upper horizontal row of contacts of the primary district switch 200. Similarly, the other horizontal rows of contacts of the secondary line switches extend as indicated by conductors, IH, M2 and H3, to other district trunks and other horizontal rows of contacts on primary district switches.

Each district trunk circuit also connects to a ertical row of contacts of a primary `sender selector switch and also to a, vertical row of contacts of a zone and timing device connecting switch. As shown, district trunk 2 I5 connects over conductors 2|3 to the right vertical contact row of primary sender selector switch 300 and also over conductors Elfi to the right vertical contact row of the zone Vand timing device connecting switch 500. A district frame is provided with ten primary and ten secondary switches interconnected by district links such as link 209, the horizontal contact rows of the secondary switches extending to an olice frame (not shown) the switches of which latter frame provide means for further extending the connection to an outgoing trunk or over a local trunk to the called subscribers line depending upon whether the call is between stations served by the same or by different exchanges.

The sender selector circuit is provided with primary switches, such as switch 300, and secondary switches, such as switch interconnected by sender links, in turn extending to subscribers register-senders, one such connection being shown from the upper horizontal contact row of secondary sender selector switch 30| over conductors` 301, to sender-308- A decoder marker connector circuit 3|0 provides for connecting the sender 300 to a decoder marker connector circuit 352. Each district frame is provided with a district frame connector circuit 320 for establishing connections between any of the one hundred district trunks served by that frame and the particular decoder marker circuit being used in establishing the connection.

In accordance with the present invention each group of district trunks appearing on a district frame is provided with a plurality of zone and time-controlled message register operating devices, such as the devices 500 to 585 inclusive, of Fig. 5, and a common control and connecting circuit such as shown in Fig. 4 for connecting an idle message-register operating device to a calling district trunk circuit, when required, and also for connecting the device to the particular decoder marker serving the call for the transmission of the necessary zone information from the marker to the timing device. The one hundred district trunks appearing on a district frame connect to the vertical rows of contacts of five zone and timing device connecting switches such as switches tot and Ziel, each connecting switch being provided with twenty vertical and ten horizontal rows of contacts. As indicated by conductors H4 and i i5 the twenty district trunks to which secondary line switches Eiill and iii have access connect to the twenty vertical Contact rows of zone and timer connecting switch i300. Similarly, the remaining eighty district trunks located on the same district frame containing district trunk 2i 5 connect to the vertical contact rows of four other connecting switches one of which, switch 46|, is shown.

The zone and timing devices, such as the devices 5Go to e535 inclusive, connect to the horizontal rows oi contacts of the connecting switches and may or may not be multipled throughout the five connecting switches depending upon the zone traffic encountered on a particular group of one hundred district trunks. Where the traiic is such that ten devices are suicie-nt to provide for timing on the maximum number of simultaneous zone calls anticipated for a group of district trunks, these ten devices are multipled throughout the horizontal contact rows of the five connecting switches in the manner in which the devices 563 and 565 are shown connected, over conductor li, to the upper ve horizontal rows of contacts of connecting switches 40| and 400. i/lfhere the anticipated zone traiic on a group of district trunks is such that more than ten zone and timing devices may be required simultaneously the multiple across the horizontal contact rows of the connecting switches is split to accommodate additional zone and timing devices as shown on the lower portion of switches 5B@ and sul. As illustrated, the multiple across the lower five horizontal rows of contacts of these stitches is split between the tenth and eleventh vertical contact rows and the corresponding lower ve left and right rows of contacts of the respective switches are multipled. With the connecting switch arrangement shown in Fig. 4 therefore, fifteen zone and timing devices are accessible to the district trunks of the district frame with which the five connecting switches represented by switches illu and @El are associated. Zone and timing devices 5G13 and 50i, representing one group of five such devices, connect over conductors M8 to the upper ve horizontal rows of contacts of switch 49! and are multipled throughout the entire iive connecting switches. Zone and timing devices 582 and 503, representing another group of ve such devices, connect over conductors i i El to the lower ve horizontal Contact rows of each connecting switch, the multiple across these contact rows, however, being split at the mid-point of each switch. Zone and timing devices iili and 5&5, representing a third group of five such devices, connect over conductors 420 to the lower five horizontal contact rows in the left half of each connecting switch.

When the subscriber at station loll initiates a call the line switch control circuit (not shown) associated with the primary and secondary iine switches H13, i013 and |05 functions to select the calling line and thereupon operates select magnet |06 of primary line switch 03. The line switch control circuit also tests the district trunk groups which may be reached over idle line links such as links H6 and li'l to determine which of these groups contain idle district trunk circuits and prefers and selects a particular group of ten district trunks if several groups are available. The sender selector control circuit (not shown) associated with the primary and secondary sender selector switches 39@ and Si!! thereupon tests the group of district trunks chosen by the line switch control circuit and selects one of these trunks which has an idle path to an available idle subscribers sender. The proper select and hold magnets of the line and sender selector switches are thereupon operated to extend the calling station line to the chosen district trunk and subscribers sender circuits.

For the purpose of this description it will be assumed that subscribers sender 388 and district trunk 2 i 5 are selected by the sender selector control circuit which therefore causes the operation oi select magnets Hi8, 302 and 304 and hold magnets iol', M39, 333 and 365 of switches E03, iol, 3,51 and 3S! respectively. Select magnet lii of primary line switch ID3 having been operated by the line switch control circuit, the operation of hold magnet EQ? closes the right upper cross-points of switch |33 and extends the calling line lili to secondary line switch HM over line link iis. The operation of select magnet iii and hold magnet H39 of switch i9@ causes the right upper cross-points of that switch to close and extend the calling line, over conductors iiil, to district trunk circuit 2l5. Select magnets 3'32 and 3BG and hold magnets 303 and 305 of the primary and secondary sender selector switches i and Sill also being operated, the calling line is also extended over conductors 253, the right upper cross-points of switch 300, sender link 336, and the left upper cross-points of switch 394, to the idle subscribers registersender 303 which latter circuit returns an audible signal to the calling station as an indication that the dialing of the desired station numb-er may proceed. The sender registers the dialed oflice designation and simultaneously causes the control circuit (not shown) of the decoder marker connector circuit Si@ to function and establish connections, by the operation of relays Si l and B2i, to an idle decoder marker circuit 3i? after which the sender transmits the wanted office designation to the decoder marker. The sender also transmits the number of the district frame to the decoder marker and this latter circuit, by means of the district frame connector 320, establishes connections between itself and the district trunk being used for the call.

From the wanted orhce designation received from the sender the decoder marker knows the destination oi the call and accordingly controls the charging operations on the basis of this information. If the destination of the call is to another subscriber served by the same exchange or by an exchange within the local area having the same rate of charge, the decoder marker 3 i2 recognizes this call as a local call and operates its local call relay SI5. The operation of relay 3H5 causes the district trunk circuit to prepare for charging the call under control of a local timing device 2te which is individual to the district trunk circuit. The manner in Which the decoder marker passes this information to the district trunk as Well as the subsequent operation of the district trunk and its associated local timing device in effecting the charging of the local call will be set forth later under the detailed description of the operation.

If the destination o1 the call is to an exchange outside of the local area the decoder marker dit, knowing this from the office code information transmitted to it from the sender 303, operates one of a plurality of zone relays M3, 3M, etc., the particular relay operated depending upon the zone in which the called station is located. It will be assumed that for the particular call under discussion, Zone relay 3i3 is operated. The function of the operated zone relay Slt will be described later. The decoder marker circuit also connects ground to conductor 3l9, this ground extending over a front Contact of the operated district frame connector relay it and over conductor Zilli to an armature of each of ten district frame relays such as relays 2li! and til, there being ten such relays per district frame, one relay being common to the ten district trunk circuits connected to each of the ten primary district Switches. These relays 2HE and 2id are operated under control of the district trunk circuits with which they are associated whenever one/of the trunks of the group is in use. Since it has been assumed that district trunk 2i5 of that group of trunks connecting to primary district switch 2t@ is being used for the connection being described, relay El@ is therefore operated under control of that district trunk circuit. Relay 2id, in operating, extends the ground previously traced to its armature, over its front Contact and over conductor 2H, to battery through the winding of a timing device connecting switch group relay 426i, operating that relay. rThe operation of relay 321i closes the test conductors of the ten timing devices which are accessible to the district trunks connected to the right half of connecting switch itil to the windings of ten test relays four of which, relays 25 to t28 inclusive, are shown. Since the zone and timing devices 5%, 553i, 5235 and 5il5 serve the district trunks connected to the right half of connecting switch 598, the operation of relay 42d therefore closes through the respective test conductors 33%, i3d and iet of these devices, over its. front contacts, to ground through the windings of test relays 25, 423, G27 and 128 respectively. Associated with each zone and timing device is a cut-through relay, such as relays 5% to 5H inclusive, the function of which is to close through the zone control conductors of the device with which it is associated to the decoder marker circuit. The windings of these cutthrough relays extend over conductors 429 to inclusive, to the front contacts of the test relays to 28 inclusive, over front contacts of the connecting switch group relays 42E to 324 inclusive, the particular ten cut-through relays connecting to the front contacts of the ten test relays at any one time depending upon which group relay is operated. For example, with relay operated as set forth above', the windings of the ten cut-through relays represented by relays iif, dill and 5m, 5M are connected to the front contacts of ten test relays represented by relays 525 to t28 inclusive, the cut-through relays 5116, 501 and 5m, 5H being associated with the Zone and timing devices 5ml, 5m and 504, 5ii5 respectively.

Relay 23 is a group relay similar in function to relay M4 but associated with that group of ten district trunks connected to the left half of connecting switch 461B, these district trunks having access, through the left half of the switch, to the ten zone and timing devices represented by devices 560, 50i and 582, 5%. The operating circuit for relay lit extends over conductor 2l8 to the front contact of district frame relay 2l l which is associated with this group of trunks connected to the left half of switch dell. Relays dit and 122 are group relays associated with connecting switch till and the district trunk groups connected thereto, and perform functions similar to those performed by relays @23 and 62d respectively. In those cases (not shown) where a maximum of ten zone and timing devices are provided for a district framel only one group relay is provided for each connecting switch since the same Zone and timing devices serve all of the district trunks connected to the connecting switches.

Each zone and timing device, when idle, connects battery to its test conductor as an indication that it is available for use. The six zone and timing devices shown in Fig. 5 are all assumed to be idle as indicated by the battery connected to test conductors 435 to MB inclusive, bythe devices do@ to 535 inclusive, respectively. When group relay [32d operates, as set forth above, all. of the test relays 525 to 323 inclusive, therefore operate due to the presence of battery on conductors G35, #336, 339 and lil. rangement later to be .disclosed in connection With the detailed description of this invention one of the operated test relays, relay l2? for example, locks in series with an end relay (not shown) this end relay operating and opening the circuits for the other operated test relays all of which release. Cut-through relay 5l@ now operates in a circuit from battery through its wind' ing, over conductor fitti, and over a front contact of relay d2@ and the front contact of relay $271 to ground. Select magnets iiii and @il of connecting switches mi and dill respectively, also operate to this same ground supplied over the front contacts of relays 42'? and 62d. rI'he select magnets of the corresponding contact level of the three other connecting switches (not shown), also operate, the corresponding level select magnets of all five connecting switches being multipled as indicated by conductors dll-l.

Each zone and timing device is provided with a plurality of zone clutch magnets such as the magnets 5i2 to tilt inclusive, of device 5M. A zone clutch magnet, when operated, locks electrically in that position and prepares the device for actuating the Zone timing cams associate-d With that particular zone clutch magnet upon the subsequent operation of the master clutch magnet of the device under control of the district trunk circuit, in a manner which will be set forth in detail later. The aforementioned operation of cutthrough relay 5l@ completes the circuits from the windings of the five clutch magnets of device 5M, over its: front contacts, conductors 322 to 326 inclusive, and over front contacts of the district frame connector relay SES to front contacts of the five decoder marker zone relays represented by relays 3l3 and 3M. Since it was assumed that Zone relay 3&3 previously operated, a circuit is therefore completed from the winding of zone clutch magnet 5l2 of device 564 to the winding In a circuit arthe contacts of the decoder marker connector relays 8i8 and 809-. The sender thereupon trans mits to the decoder marker such information regarding the destination of the call as this latter circuit requires for performing its functions in the extension of the connection. Information is also passed from the sender to the decoder marker regarding the number of the district frame containing the particular district trunk circuit selected for use on this call, and the decoder marker thereupon establishes connections between itself fand that district frame by operating the district frame connector relay 8i2. From the office code information received from the sender the decoder marker knows whether or not the call is to a station within the local area, and, if it is a local area call, operates its local area relay 818. If the call is not within the local area, the decoder marker operates one of its zone relays 8I9, 820, the particular zone relay operated depending upon the Zone in which the exchange serving the called station is located.

It Will rst be assumed that the call under discussion is between exchanges within the local area; the decoder marker therefore operates the local area relay SiS. The decoder marker, at the time of its connection with the district trunk over the sender selector switches, also operated its relay 8H thereby operating relay mi of the district trunk in a circuit traceable from battery through the winding of relay 52d, over the right back contact of relay 22, conductor lowest contacts of the sender selector prima-ry and sec ondary switch crossfpoints Beil and 8.2M, through the sender 8537 and the lowest contacts of decoder marker connector relays 85.18 and B539, to ground over the front contact of relay Si l. With relay 62! operated a circuit is completed from battery through the winding of relay 322 oi the district trunk circuit, over the left inner front contact of relay 625, conductor 856, a front conta-ct of district frame connector relay 852, and over the front contact of relay 3l3 to the windings of a polarized trouble detecting relay B2i. The two windings of relay 82 are so connected that they oppose each other electrically and these windings are normally energized in acircuit from battery through the windings in series to` ground through resistance B22. The left winding of relay 82E is provided with a -greater number of turns than the right winding and is so connected that the greater force which it exerts upon the relay armature over that exerted by the right winding tends to hold the relay in the unoperated position before the circuit to the junction of its windings is closed by the operation of relay 8i8. When relay S58 operates, as set forth above, the left winding of relay 82! is shunted by the battery supplied through the winding of relay 622, provided that the circuit extending from the winding of relay 622 to the armature of relay 8| 8 is complete and is not falsely grounded, thereby allowing relay B2i to operate under control of the force exerted by its right winding. The operation of relay 82| operates relay 823 in a local circuit. Relay 823, in operating, locks over its left inner front contact under control of another decoder marker relay (not shown) and connects ground directly to the right winding of relay 82! thereby short-circuiting resistance 822. Relay 522 of the district trunk, which did not receive sufcient current to operate in series with the right winding of relay B2i and resistance S22, now operates and locks over its right inner front contact to an olf-normal ground supplied over the front contact of a previously operated district trunk relay 523. Relay S2 remains locked upon the operation of relay 622, in a circuit over its right inner` front contact, conductor 5l5, a front contact of connector relay 3i 2, to ground over the front contact of decoder marker relay 826, which previously operated. The closure of the locking circuit for relay S22 short-circuits the right winding or" relay 322i of the decoder marker and this latter relay there-upon releases due to the force exerted by its lef t winding. The release of relay 32| completes a circuit from ground over its back contact, over the left outer front contact of relay 823, over the back contact of relay 82d, and over conductor 325 to a relay (not shown) of the decoder marker which records the fact that the local area call charging information has been passed to the district trunk by the operation of relay '322 of that trunk. The decoder marker circuit thereupon proceeds with its functions in extending the connection. Select magnets '103 and 'H25 and hold magnets me and l' of the primary and secondary district frame switches are operated under control of the decoder marker thereby causing the closure of cross-points 'ilil and and extending the connection over district link 'iti-i to the oce frame switches (not shown). The connection to the called station lol is completed over the ofc incoming and nal switch circuits (not shown) under control of the decoder marker and the sender in the manner described in the aforementioned copending application of W. W. Carpenter, Serial No. 27,305.

Upon the aforementioned operation of relay 522 a circuit is closed from battery through the winding of clutch magnet 524 of the local timing device GES, over the left inner front Contact of relay 22, to the front contact of the called station supervisory relay 525 of the district trunk circuit. A circuit is also completed from ground through the winding of the message register 602 which is associated with the calling station line Sill, over the lowest contacts of the primary and secondary line switch cross-point 583 and 6M, conductor 646, left outer iront contact of relay $22, and over the normally closed contacts associated with the charging cam 626 to ground thereby short-circuiting the message register GGZ to prevent any possibility of its false operation prior to the charging of the call.

When the called subscriber answers, supervisory relay 625 operates and completes the operating circuit from clutch magnet 621i to the ground over its front contact and armature. The operation of magnet 526 disengages the armature 63! from the clutch cam 532 and permits clutch S333 to function and engage driving shafts 630 and 63s. Shaft E38 is rotated continuously by a synchronous motor and this motion is transmitted, upon the engaging of shaft with shaft 63d, over the reduction gears 535 and S32? to shaft 637 and its associated interrupter cams 626, 621 and G28. As soon as shaft 63's starts to rotate, the off-normal cam $28 causes its associa-ted contacts 644 to open thereby opening the circuit between the left inner back Contact of relay 622 and conductor 341, this conductor being the zone and timing device start conductor extending to a set of cross-point contacts on one of the zone and timing device connecting switches. This aforementioned circuit is opened to prevent the starting of a zone and timing device in connection with a Zone call if the local timing device associated with the district trunk circuit over of a check relay 3 f6 of the decoder marker. The decoder marker at this time makes certain check tests which will be described later and thereupon causes Zone clutch magnet 5l2 to operate and lock, thereby preparing device 504 for subsequently transmitting charging pulses in accordance with the zone information recorded in the decoder marker.

As previously stated, each of the one hundred district trunks of a district frame connects to one vertical row of contacts of one of the ve connecting switches, such as switches 400 and 40|. A hold magnet such as magnets 402 to 405 inclusive, of switch 400 and magnets 4 l 0 and 4 l 3 inclusive, of switch 40| is associated with each vertical row of contacts of each switch, there being twenty such hold magnets per switch. Following the aforementioned operation of the end relay (not shown) which operates in series with test relay 421, a circuit is completed for operating hold magnet 405 of switch 400, it being assumed that magnet 405 is associated with that vertical row of contacts in the right half of switch 400 to which district trunk 2HE: is connected. The operating circuit for magnet 455 will subsequently be described under the detailed operation of the invention. Select magnet 409 having previously operated together with the corresponding selectl magnets oi the four other connecting switches, the operation of hol-d magnet 405 causes crosspoint contacts 442 of switch 12300 to close and thereby establish connection between the selected zone and timingdevice 504 and the district trunk circuit 2l5.

After operating the Zone clutch magnet 5l2 of device 504 and -checking that this magnet has properly locked, the decoder marker proceeds to extend the connection. Select magnet 204 oi the primary district switch 200 is operated under control oi district trunk 2l5. Hold magnet 205 of switch 200 as well as select magnet 200 and hold magnet 201 of the, secondary district switch are operated by the decoder marker thereby causing the closure of cross-points 208 of switch 200 and crosspoints 2l2 of switch 202. The connection is thus extended from district trunk 2l5, over district link 209, and over conductor 299 to an oce frame (not shown). The connection is further extended over the office frame switches and an outgoing trunk (not shown) under control of the decoder marker. The connection to the called subscribers station is completed by the various circuits (not shown) at the distant exchange under control of the subscribers register-sender 3300. For a description of these circuits which have not been shown, as well as the manner of their operation in completing the connection, reference may be had to the aforementioned copending application of Carpenter, Serial No. 27.305, led June 19, 1935.

When the called subscriber answers the call, the district trunk circuit 215 functions in a manner which will subsequently be described and energizes the master clutch (not shown) of the l device 504. The device 5% thereupon functions and transmits the proper charge pulses, under control of cam 5l8 which is associated with the operated zone clutch magnet 5I2, over the district trunk circuit, and back to the message register |02 of the calling station line 10|.

The decoder marker circuit, after it has transmitted the necessary Zone information to the zone and timing device 504, removes the ground from the armature of relay 2H) of the district frame, thereby releasing relay 424. The release of relay 424 releases relay 5l ll and the select magnets 409, 4I1 etc., of the ve connecting switches. Hold magnet 405 remains locked under control of the district trunk circuit until the termination of the connection between the subscribers after which the district trunk releases the hold magnet, thereby restoring the connecting switch cross-points 442 to normal.

Referring now to Figs. 6 to 10 inclusive, a detailed description of the operation of this system will be given. Assuming that the subscriber at dial station 600 initiates a call, the closure of the loop of line 60| due to the removal of the receiver from the switchhook at station 500 causes line relay 606 to operate in a circuit extending over the back contacts of cut-ofi:` relay 605. The operation of relay 606 closes in part the operating circuit for hold magnet v601, this magnet beassociated with that vertical row of primary line switch contacts to which the calling line 00! is connected, and also grounds conductor 0M which extends to the associated line switch control circuit (not shown). The line switch control circuit and the sender selector control circuit (not shown) now function and extend the calling line to an idle district trunk circuit and to an idle subscribers register-sender. For a detailed description of the circuits involved in the establishment of these connections between the calling line and the district trunk and subscribers sender, reference may be had to the copending application of W. W. Carpenter, Serial No. 27,305, filed June 19, 1935.

For the purposes of this description it will be assumed that the district trunk 048 and the indicated subscribers register-sender 801 are selected for use on the call under discussion by the aforementioned operations of the line switch and sender selector control circuits, these control circuits thereupon completing operating circuits for select magnet 608 and hold magnet 601 of the primary line switch, select magnet 6H and hold magnet 6H) of the secondary line switch, select magnet 003 and hold magnet 802 of the primary sender .selector switch, and select magnet 805 and hold magnet 804 of the secondary sender selector switch. The operation of select magnet 608 and hold magnet 601 causes cross-points 603 of the primary line switch to operate, while the operation of select magnet 6H and hold magnet 640 operates the secondary line switch crosspoints 604. The calling line 60| is thereby eX- tended, over cross-points 603, line link 513, and cross-points 604, to district trunk 6|5 and also over conductors 6 I1, GIB and GIS, to the primary district frame switch upon which cross-points 100 appear. The operation of select magnet 803 and hold magnet 802 of the primary sender selectorswitch closes cross-points 800 of that switch, while the operation of select magnet 805 and hold magnet 004 closes cross-points 8M of the secondary sender selector switch.l The calling line 60| and the district trunk circuit 048 are therefore also` extended, over primary sender selector switch cross-points 800, sender link 806, and over the secondary sender selector switch` cross-points 80! to the subscribers registersender 801, this sender thereupon returning an audible indication to the calling station that dialing may proceed.

The designation of the wanted station, as dialed by the calling subscriber, is recorded on the register mechanism of the sender 001 which, after it has recorded a portion of the number, associates itself with an idle decoder marker 8l0 over which the zone call is being extended is not in its normal position, thus eliminating the possibility of a double charge in the event that the local timing device of the district trunk is functioning, due

to a trouble condition, at the time that the district trunk is being used for a zone call.

Holding cam 62'iy functions shortly after shaft 66? starts rotating and closes its associated contacts 662 thereby locking the clutch magnet 626 for the duration of the timing interval regardless of any momentary releases oi supervisory relay 625 due to switch-hook liashing at the called station. This locking circuit for magnet 626 is traceable from battery through the magnet and over its front contact, over contacts 642 of hold cam 62?, over the right inner front relay 622, to an off-normal ground supplied over the front contact of relay 623. As shaft 631i continues to rotate, the charging cam 626 actuates its associated contacts 663 for a brief interval and then restores these contacts to their normal position. During this charging interval the opening of the lower contact of springs 663 removes the groun-d from conductor 613B while the closure of the upper contact of these springs connects battery through resistance 638 to conductor 6456 and over a previously traced circuit to the winding of message register 662 thereby causing the register to operate and record one local call. Upon the restoring of springs 663 ground is once more connected toI conductor 646 thus again placing a short circuit around the winding of message register 662. Shaft 631 and its attached cams 626, 62'? and 62S make one complete revolution for each time charge interval and continue to rotate as long as the subscribers remain in communication. Although hold cam 62'? causes its associated contacts 642 to open the locking circuit for clutch magnet 626 at the completion of each revolution of shaft 667i, the clutch magnet remains energized during the open interval of contacts 642, over its original operating circuit to the ground over the front contact of the calling supervisory relay 625 as long as the subscribers remain in communication. The functioning of charging cam 626 and its associated contacts BGS cause one pulse of battery to be connected over conductor 64|) to the message register 602 for each overtime charge interval thereby causing that register to record the additional charge.

Whenever the calling subscriber places his receiver back on the switch-hook, relay 623 of the district trunk circuit releases, in turn releasing relay 622 which opens the operating and locking circuits for clutch magnet 626. The timing device 6|6 is so constructed that the release of magnet 621i causes the shafts 634 and 631 and their attached cams to immediately restore to normal regardless of the position of these shafts and cams at the time that magnet 624 is deenergized. This immediate restoring is accomplished mechanically by means of a spring (not shown) which winds up during the initial revolution of shaft 634. The purpose of restoring the timing device to normal at once is to enable the district trunk circuit with which the device is associated to be immediately available for use in connection with another call. When clutch magnet 626 deenergizes, armature 63| is restored to its original position by spring 639 and engages the clutch cam 632 thereby preventing any further motion of shafts 634 and 63? and thus restoring the timing device 6| 6 to normal.

In the event that the calling subscriber remains connected to the district trunk circuit after the called subscriber has replaced his receiver, clutch magnet 624 remains energized over its locking circuit until cam 621 opens contacts 662 at the completion of the particular timing interval being measured. Upon the opening of contacts 662 clutch magnet 624 deenergizes, since its original energizing circuit is open due to the previous release of the called station supervisory relay 625, and the timing device thereupon restores to normal mechanically as set forth above. Should the called subscriber again remove his receiver from the switch-hook at this time the subsequent operation of relay 625 closesthe energizing circuit for clutch magnet 624 and the charging and timing for the next interval will immediately begin.

When the district trunk circuit relay 623 releases upon the replacing of the calling subscribers receiver on the switch-hooi', ground is removed from the holding conductor 6|9 thereby releasing the operated hold magnets 667, 6MB, '|64 and '|66 of the line and district frame switches thus causing cross-point contacts 663, 666, 766 and 'ii of these switches to restore to normal. The select magnets associated with the horizontal rows of contacts containing these crosspointsyas well as the sen-der selector switch select magnets 803 and 805 and hold magnets 862 and 864, previously released at the time that the line switch and sender selector control circuits restored to normal.

The charging and timing operations involved in recording a local area call on the calling subscribers message register having been described, it will now be assumed that the call initiated by the calling station 660 is to a station served by an exchange located outside of the local call area. The connections between the calling subscribers line 66|, district trunk 666, sender 86T and decoder marker SIU, as well as the connections between decoder marker Bill and the district trunk and district frame over the district frame connector relay 8|2, are established in the manner identical with that hereinbeiore described in connection with the local area call. The decoder marker 8|0, knowing from the oice code information transmitted to it by the sender that this is a zone call, operates one of its zone relays, such as relays BIS and B20, the particular zone relay operating being dependent upon the zone in which the called station exchange is located. It will be assumed for the call being described that decoder marker zone relay @i6 operates.

Following the establishment of connections between the district trunk and the decoder marker, district trunk relay 62| operates in a previously traced circuit extending over the sender selector switches and the sender to a ground over the front contact of the operated decoder marker relay Si l. Relay 62|, in operating, closes in part the operating circuit for hold magnet 666 of the zone and timing device connecting switch 96|, this hold magnet 966 being associated with that vertical row of contacts of switch 6.6i tc which district trunk 648 connects. This operating circuit is traceable from battery through the winding of magnet 966, over conductor 90?, left outer front contact of relay 62|, conductor 66S, to the front contact of relay 969 which is unoperated at this time. Relay 62| also closes a circuit from ground over its right outer front contact and over conductor 645 to battery through the winding of district frame relay '|68 which is common to that group of ten district trunk circuits,

including trunk 648, which extend to the same primary district frame switch and which also connects to the ten vertical rows of contacts in the left half of Zone and timing device connecting switch 963i of Fig. 9. Relay 198 operates and completes the operating circuit for group relay 992 of the timer connecting switch. This operating circuit is traceable from ground over the right front contact of the operated zone relay 8l9, a front contact of connector relay BIZ, conductor 8H, front contact of relay 108, conductor 813, to battery through the winding of relay 992. Relays 'm9, il@ and lll are other district frame relays, similar to relay 198, associated with other groups of ten district trunks. The front contacts oi' relays 109, 'H9 and 'HI extend over conductors 8M, 82'! and 828 to the windings of zone and timing device connecting switch group relays 993, 994 .and 9il5 respectively. Group relays 93, 9534 and 995 perform functions, in connection with the district trunk groups with which they are associated, identical with those performed by relay 902 as hereinafter described.

IThe operation oi relay 9&2 closes circuits from the test conductors of the ten zone and timing devices accessible to the ten district trunks connected to the left half of connecting switch 99E! to the windings of ten test relays of which four, relays Qiii to 9i3 inclusive, are shown. As hereinbefore stated in the general description, an idle zone and timing device has battery connected to its test conductor and therefore operates its associated test relay. Assuming that the zone and timing device i990, partly shown 'in the up-per portion of Fig. l0, is idle at this time,

test relay 953 operates in a circuit traceable from,

ground over the back contact of relay 9M, lower winding of relay 923, lower inner front contact of group relay 992, conductor 9l5, over the back contact of Zone clutch magnet wel, conductor will over back contacts of three other zone clutch magnets (not shown), and over the back contact or" Zone clutch magnet i993, to batteryl through resistance iilll. The ground over the back contact of relay 9M also extends through thelower windings of the other test relays, such as relays 9M), 9i l and 982, over other lower front contacts of relay 992, to test `conductors 9I6, 9H and 958 respectively, which extend to other zone and timing devices (not shown). Any test relay having .an idle timing device connected to its winding will therefore operate. For the purpose of this description it will-be assumed that only the device iilill is idle. Upon the operation of group relay 992 therefore, test relay 93 alone operates. Relay SES, in operating, locks in a circuit from the battery previously traced to conductor G55, through its upper winding and over its inner front contact, inner back contacts of the unoperated test relays SI2, 9H and Sill), in that order, and over the lower next-to-outer contact of relay 962 to ground through the winding of end relay 9M. Relay 9M operates in series with the upper winding of relay 9I3 and removes ground from the lower windings of all of the test relays thereby causing 'the release of all operated test relays, with the exception of the test relay which is locked in series with end relay 9M, in those cases where more than one test relay operates.

It will be noted that the locking circuit for each test relay extends over its inner front contact to the winding of end relay 9| 4 either tlirectly over a front contact of `the group relay shown directly above that test relay or over a chain circuit extending over the inner back contacts of the other test relays and the front Contact of whichever group relay is operated. This arrangement provides a preference in the selection of a zone and timing device if more than one device is idle, a particular group relay always preferring a particular timing device, if available. Each group relay connects the inner armature of a different test relay directly to the winding of end relay 9M thereby providing a direct locking circuit for that test relay in the event that it operates due to its associated device being idle. In this manner each group prefers the zone and timing devices in a different order thereby distributing the use of these devices evenly.

When end relay 9M operates in series with test relay 943 as hereinbefore described, it energizes slow-tO-operate relay 9il9 and also closes a circuit from ground over its front contact, lower outer front contact of relay 992, outer back contacts of relays SIU, 9i l and SI2, outer front co-ntact of relay 9i3, front contact 959 of relay 982, to battery through the winding of select magnet figli of connecting switch 9m. This same ground also extends over conductor 92E to battery through the Winding of cut-through relay i996 which is associated with the Zone and timing' device i999. Relays i985 and will to llil inclusive represent cut-through relays associated with other Zone and timing devices (not shown). Select magnet 929 of switch Sill operates and prepares the upper row of cross-point contacts of that switch for operation. Slow-tooperate relay 999 now operates and closes a circuit from ground over its front contact, over conductor 908, left outer front contact of district trunk relay $52!, conductor 9U?, to battery through the winding of hold magnet Sli@k of switch sill. Magnet 99.5 operates and, since select magnet 929 is already operated, closes cross-point contacts 922 of switch 9M thereby connecting district trunk @I to Zone and timing device i000 over conductors 6M and 947 and lell and i042 respectively.

At the time that select magnet 929 of switch 995 operates, the select magnets of the corresponding levels of the other connecting switches, suchas magnet 92A of switch 9539, also operate, the windings of these magnets being multiplied together. Since only hold magnet 9de of switch 994 operates at this time, the cross-point contacts of the other connecting switches do not operate. Relay 989 is made slow-to-operate to provide sufcient time for the connecting switch select magnets, such as magnets 92@ and 9W, to operate before the hold magnet circuit is closed thereby insuring the proper operation of the connecting switch cross-points. As indicated by multiple strap @i6 at the left outer front ccntact of district trunk relay @EL conductor 998 from the front Contact of relay 999 connects to the left outer front contact of each of the one hundred district trunk relays identical to relay 625. Only one zone and timing device connecting switch hold magnet operates at a time however since only one relay, such as relay 62l, of the one hundred district trunks of a district frame is operated at any particular time.

Upon the operation of cross-points 922 ground is connected, over the lowest contact set of those cross-points, to conductor M5 thereby short-circuiting test relay 9l3 and end relay 9M both of which release. The release of relay 9M releases relay 909 which in turn opens the previously traced operating circuit for hold magnet 906. Magnet 986 remains locked in a circuit from battery through its winding and over its front contact, conductor 923, to ground over the front contact of the operated relay 623 of the district trunk circuit. The release of relay 9|4 opens the original operating circuit for cut-through relay |006 and select magnet 920, this relay and select magnet now remaining locked over the upper inner front contact of relay 006, conductor |025, upper front contact of the operated group relay 902, to the previously traced operating ground for relay 902 over conductor 8|3.

Each zone and timing device, such as the device |000 of Fig. 10, is provide-d with a plurality of Zone clutch magnets and one master clutch magnet. It is assumed that device |000 is arranged to transmit five different sets of zone charge pulses and the device is therefore provided with ve zone clutch magnets two of which, magnets |00| and |003, are shown. Magnet |0|4 is the master clutch magnet for the device |000. 'I'he aforementioned operation of cut-through relay |006 closes circuits from each of the ve Zone clutch magnet windings to the left armatures of the decoder marker Zone relays 8|9, 820. The circuit for zone clutch magnet 00| may be traced from battery through the winding of that magnet, over the lower next-to-outer front contact of relay |006, conductor |0I5, a front contact of connector relay 8| 2, and over the left front contact of the operated zone relay 8|9 to the windings of polarized relay 82|. As hereinbefore described in connection with the charging of a local area call, relay 82| is normally energized in a circuit from battery through its windings in series to ground through resistance 822, the left winding of the relay exerting a greater force than the right winding and thereby holding the relay in its unoperated position. If the circuit extending from the winding of zone clutch magnet |00| to the windings of relay 82| is complete and not falsely grounded, the battery through that magnet shunts the left winding of relay 82| and that relay thereupon operates under control of the force exerted by its right winding. Zone clutch magnet |00| does not operate at this time due to the current limiting effect of resistance 822 which is in series with the right winding of relay 82| and the clutch magnet. The operation of relay 82| operates relay 023 locally. Relay 823 locks under control of another decoder marker relay (not shown) and connects direct ground to the rightwinding of relay 82| thereby short-circuiting resistance 822 and allowing zone clutch magnet |00| to receive sufficient current to operate.

In operating, Zone clutch magnet |00| locks over its front contact and over conductor 9|5 to ground over the lowest Contact of the operated cross-point 922 of switch 90|. The closure of this locking circuit connects direct ground toy conductor |0|5 thereby short-circuiting the right winding of relay 82| which thereupon releases due to the force exerted by its left winding. Relay 82 in releasing, closes a circuit from ground over its back contact, over the left outer front contact of relay 823, back contact of relay 824 and over conductor 825 to a relay (not shown) of the decoder marker which operates and records the fact that the zone clutch magnet of the timing device has properly locked. Conductors i0 i6 to |0| 9 inclusive, which extend from the windings of the four other Zone clutch magnets of device |000 over front contacts of relay |006 to the left armatures of the unoperated decoder marker zone relays such as relay 820, connect over the left back contacts of these zone relays to battery through the winding of a trouble detecting relay 824. Should a false ground be present on any of the unused Zone clutch magnet conductors the trouble detecting relay 024 will operate. If operating, relay 824 opens the circuit over conductor 825 thereby preventing the decoder marker from proceeding any further in the extension of the connection. The operation of relay 824 also connects ground to conductor 829 which causes the decoder marker to function and record a trouble condition.

At the time that cut-through relay |006 operates and establishes connections between the Zone and timing device |000 and the decoder marker 8|2 it also completes a testing circuit for checking that the district trunk circuit 6|5 is connected through to but one zone and timing device, i. e., the device |000. This testing circuit extends from battery through the winding of relay |029, over the upper outer front contact of relay |006, conductor |0|3, to the armature of contact set 925 of cross-points 922. Since crosspoints 922 are operated this battery through the winding of relay |020 is further extended to the front contacts of contact sets 929, 930 and 93| of cross-points 926, 921, and 928, respectively. The armatures of Contact sets 929, 930, and 93| extend, over conductors 932, 933, and 934, to the upper outer armatures of cut-through relays |005, |001, and |008, respectively, and, since these relays are unoperated at this time, ground over their back contacts is connected to the armatures of cross-point contact sets 929, 930, and 93|. In the event that a second set of crosspoints in the same vertical row with cross-points 922 is falsely operated at this time, relay |020 operates over conductor |0|3, cross-point 925, the cross-point 929, 930, or 93| of the falsely operated set, to ground over conductor 932, 933, or 934 as the case may be. The operation of relay |020 lights an associated lamp |02| as an indication of the double-connection encountered and also operates alarm relay |022 in a circuit from battery through the winding of that relay, back contact of key |023, to ground over its right front contact. The operation of relay |022 grounds conductor |024 which causes an audible alarm (not shown) tosound; connects a ground over its middle front contact, over conductor |025, to the upper front Contact of group relay 902 to lock that relay; and completes a circuit from ground over its outer front contact, conductor |026, a front contact of relay 8|2, to conductor 830 of the decoder marker 8|0 for the purpose of informing the decoder marker that a trouble condition has been encountered during the selection of a zone and timing device.

If, at the time that cut-through relay |006 operates, the master clutch magnet I0 I4 of device |009 is prematurely operated due to a trouble condition, trouble detecting relay |021 operates in a circuit from battery through its winding, over the lower outer front contact of relay |006, to ground over the front contact of magnet |0|4. The operation of relay |021 lights an associated alarm lamp |028 and also operates alarm relay |022 over the back contact of key |023. Alarm relay |022 functions as previously set forth, causing an audible alarm (not shown) to sound, locking group relay 902 operated, and grounding conductor 830 of the decoder marker to inform that circuit of the trouble encountered. While a trouble condition is being cleared the locking type key |023 may be operated to release the alarm relay vand thereby silence the audible alarm. ,An associated lamp I 020 lights whenever key |023 is Vin the operated position.

After the decoder marker 0| 0 has recorded the fact'v that the zone clutch magnet |00| has properly operated and locked, as indicated by the release of its relay 82|, and, assuming that none of the other `trouble conditions set forth above have been encountered, the decoder marker releases its operated Zone relay BIS and proceeds with its functions. The connection to the called station '|0'I` isestablished in the same manner as previously'described in connection with the local yarea call. The release of relay 0|9 removes the ground from conductor 0|0, the armature of relay 700, and conductor S, thereby releasing group relay 902, cut-through relay |006 and select magnet'920. `'Ihe release of relay |000 opens the circuits from the windings of the zone clutch magnets of device |000 to the decoder marker 8|0 and also opens the circuit to the winding of trouble detecting relay |027 thereby restoring the control and testing equipment associated with the Zone and timing devices and with the connecting switches to normal,

Atthe time that Zone clutch magnet I 00| operates-and locks as hereinbefore set forth, it disengages its vupper armature from the initial charge clutch release cam |04| and also, due to the movement of its lower inner armature, causes latch |044 to move upward into a position such that this latch'will engage the tooth of cam |0143 after thislattercam hascompleted one revolution. By these aforementioned operations those portions ofthe Zone and timing device |000 which arev associated with the ZoneV clutch magnet |00| areprepared for functioning upon the subsequent operation of the master clutch magnet |0I4.

Whenthe call is answered by the subscriber at station 107|, the called party supervisory relay 625 of the district trunk circuit operates and completes a circuit from ground over its front contact, overfthe left inner front contact of relay 622, contactsiil of the local timing device 0|6 providing-'that this local timing device is normal', over conductor 04|, contacts 935 of the operated connecting switch cross-points 922, conductor |0| 2, to battery through the winding of start relay |030. Relay |030 operates and closes an obvious circuit for energizing the master clutch magnet 0| 4 which disengages its upper armaturel from Ythe master clutch release cam |03|. Synchronous motor |032 and its attached shaftY |030 arerunning continuously and, upon the release of cam |03! by the operation of magnet I0|4, the motion ofY shaft I 030 is imparted to shaft v|004 through the action of the master clutch |007.l This motion is further imparted through the `reduction gears |035 and |030 to shaft |008.. parted to shaft |042 throughthe action of clutch |045, shaft |042 being free to move since the operation of zone clutch magnet |00| causedV the freeingof release cam |04| as previously stated. As soon as shaft |038 starts to rotate, holding 7() cam |030 functions and closes its associated contacts'thereby completing a locking circuit fork the master clutch magnet lill/5. This locking circuit isf-.traceable from battery through the winding of magnet |0I4, over the contacts associated with .cam |000, conductor SI5, to ground The motion of shaft |039 is ini-- over the lowest set of contacts of the operated cross-points 922 'of switch 90|. Immediately after shaft |042 starts to rotate, the teeth of cam |046 actuate the initial charge contacts |041 which connect pulses of battery, supplied through resistance |048, to conductor |0| I. These battery pulses extend over the upper set of contacts of cross-points 922, conductor 041, left outer back contact of relay 022, to conductor 040, which extends over a previously traced circuit to the winding of the subscribers message register 002. Since cam |040 is provided With four teeth, register E02 therefore operates four times and thereby records the initial charge for the zone call being made. Cam |051, which is associated with the zone clutch magnet |003, represents the initial charge cam for some other zone and is provided with ve teeth, as shown.

As shaft |042 completes its revolution at the end of the initial conversation period, the tooth of cam |043 engages the latch |044 and forces that latch and the associated rod |040 to the left until the motion of rod |049 is stopped by the pin |056. Since latch |044 cannot move any further to the left it stops the motion of cam |043 and also of shaft |042 and cams |04| and |046. The movement of rod |049 to the left causes latch |050 to disengage from thev tooth of the overtime charge release cam |05|. Shaft |052 now rotates in unison with shaft |038, the coupling between these shafts being supplied by clutch |053-, Immediately after shaft |052 starts rotating the overtimecharge cam |054 actuates the overtime charge contacts |050, the two teeth of cam |054 causing two pulses of battery, supplied through resistance |055, to be transmitted to the winding of the subscribers message register 602 over a previously traced circuit. Register 002 operates twice and thereby records the charge for the first overtime period. Shaft |052 and its attached cams |05! and |054 make one completev revolution for each overtime conversation period yand continue to rotate as long as the subscribers remain in communition with eachother. Immediately after the start of each additional overtime period cam |054 and springs |058 function and transmit charging pulses for that overtime period in the same manner as has already been described for the initial overtime period. Although hold cam |030 causes its associated contacts to open the locking circuit for the master clutch magnet 0 i4 at the completion of each revolution of shaft |038, the master clutch magnet remains energized during the open interval of the hold cam contacts over its original operating circuit as long as the called subscriber remains connected and relays 625 and |030 remain operated.

When the calling subscriber replaces his receiver on the switch-hook, relay 023 of the district trunk circuit releases and removes the ground from conductors 0|9 and 923. The removal of ground from conductor 6|9 releases hold'magnets 601, 6|0, '|04 and '|00 of the line and district frame switches thereby restoring cross-points 603,- 604, '|00 and 10| of these switches to normal. The removal of ground from conductor 923 opens the locking circuit for hold magnet 906 vof switch 90|. Hold magnet 906 releases and restores cross-points 922 to normal. The restoring of cross-points 922 opens the operating circuit for relay |030 which now releases if it has not already done so due to the called subscriber disconnecting lbefore the calling subscriber.. The release of relay |030 opens the orig- 

